RD & QC Compression

Designed to be centered on the loading axis of a RD or QC test machine load frame, compression platens provide a hardened surface (Rockwell HRC 58/60) for complex compression tests in which uniform stress distribution is critical. Plane and spherically seated compression platens are available in a range of diameters.

Designed to mount directly to the table or upper head of the frame, compression platens are available with numerous types of adapters, making them compatible with a wide range of testing platforms.

Cube and Cylinder Fixtures typically consist of an upper spherical compression platen that is used in conjunction with existing machine spacers and lower platens. In the case of cube fixtures being used on large capacity frames, an additional lower sub-platen may be included. These fixtures are used to apply a compressive force to a specifically sized cube or cylinder.

Splitting Tensile fixtures are used for splitting cylinders along the length of the cylinder to determine their splitting tensile strength. The fixture has an upper splitting head with a bearing bar surface that is free to tilt 4 degrees along the length of the cylinder. Applying a compressive load with this fixture induces tensile stresses on the plane containing the applied load.

Principle Of Operation

The high Rockwell Scale hardness of the compression platens ensures lack of deformity at pressures up to their capacity. Their inscribed concentric circles ensure proper, centered placement of the specimen, thereby increasing the validity of test results. A level seating surface and even load distribution over the specimen is ensured due to the high tolerance in the flatness of the surface. This aids the operator in attaining valid test results and true failure measurements.

The spherically seated compression platen is designed to accommodate angular displacement (up to 4 degrees) of the top of the specimen with reference to the machine’s loading axis. This is accomplished through the spherical seating of the platen and the metal springs connecting the platen and the base. Spherically seated compression platens are typically mounted to the upper frame of RD or QC machines. They are normally used in conjunction with a plane compression platen that is mounted to the machine's piston or table.

When compression platens are used for testing concrete cylinders, it may be necessary to use customer supplied sulfur or pad endcaps if the specimen loading surface is uneven. These caps, when used in conjunction with a spherically seated and a plane compression platen, will provide a flat loading surface that will uniformly distribute the load applied to the specimen, thus preventing premature failure of the specimen due to uneven loading.

The Splitting Tensile fixture applies a force along the longitudinal surface of a cylinder, usually against the machine lower table. Thin strips of plywood are used on the top and bottom sides of the cylinder to evenly distribute the force against the cylinder.